The present invention relates to an elbow which can be suitably connected mainly to the bent piping portions of pipe bodies, and a method for manufacturing the same elbow. Although the present invention does not relate directly to the sizes of the diameters of pipe bodies, the present invention particularly relates to an elbow which is suitably connected mainly to the bent piping portions of large-sized pipe bodies having a large inside diameter, for example 1,000 mm, 2,000 mm and so on.
Conventionally, in an elbow of the above type and a method for manufacturing the same, as shown in FIGS. 11 to 16, a synthetic resin pipe body P having a required length and including a spirally corrugated pipe wall 1 is cut and divided along a cut line C having a required inclination angle in the inclined direction thereof to thereby produce two pipe bodies, one of the thus cut and divided two pipe bodies is turned in the circumferential direction of the pipe body P with respect to the other to thereby change the relative angles of the cut surfaces of the pipe body, and the cut end faces of the two pipe bodies are butted against each other and are then connected together in a watertight manner. (For example, refer Japanese Patent Examined Publication No. Hei. 4-44157, especially, a structure shown in FIG. 1 thereof).
Describing the above structure more concretely with reference to the accompanying drawings, to manufacture an elbow E having an angle of 45xc2x0 shown in FIG. 13, as shown in FIG. 11, the middle portion of a blank material, that is, a spirally corrugated synthetic resin pipe body P, which has been cut to a required length, is cut and divided along a cut line C inclined at an angle of 22.5xc2x0 with respect to an intersection line in the longitudinal direction thereof to thereby provide two pipe bodies p, pxe2x80x2. Next, of the thus divided two pipe bodies p, pxe2x80x2, one pipe body pxe2x80x2(in the case of FIG. 12, a pipe body shown on the right side thereof) is turned by an angle of 180xc2x0 in the circumferential direction thereof to change the relative angles of the cut surfaces of the pipe bodies p, pxe2x80x2 in such a manner that the cut surfaces of the two divided pipe bodies p, pxe2x80x2 can have a V-like shape when it is viewed from the side surface side thereof; next, the respective cut end faces of the two pipe bodies p, pxe2x80x2 are butted against each other (FIG. 12); the whole peripheries of the thus butted surfaces F are connected together by wire members w such as wires which are disposed at two or more portions of the butted surfaces F so as to extend across the two sides of the respective butted surfaces F; a sheet-shaped connecting material g formed of blank material, which has the same property as the material of the pipe body P and is highly fusion-weldable to the pipe body P material, is heated and melted and is then stuck onto the outer peripheries of the thus-connected butted surfaces F in several layers, thereby closing or sealing spaces formed on the spirally corrugated cut surfaces of the butted surfaces F over the whole peripheries of the pipe bodies; and, the inner surface sides of the pipe bodies are also sealed similarly to thereby connect together the two pipe bodies p, pxe2x80x2 in a watertight manner. That is, the elbow E is manufactured in this manner.
Now, FIGS. 14 to 16 show means for manufacturing an elbow E having a bending angle of 90xc2x0 shown in FIG. 16. As shown in FIG. 14, a blank material, that is, a synthetic resin pipe body P is cut on the two sides of the middle portion of the pipe body P along cut lines C, C respectively inclined at an angle of 22.5xc2x0 and at an angle of xe2x88x9222.5xc2x0 with respect to an intersection line in the longitudinal direction of the pipe body P; with the thus obtained middle portion pipe body pxe2x80x2 left unchanged as it is, the two-side pipe bodies p, p are respectively turned by an angle of 180xc2x0 in the circumferential direction thereof to thereby change the relative angles of their respective cut surfaces; next, the thus angle-changed cut surfaces are butted against each other (FIG. 15); and, the respective butted surfaces F, F are connected together in a watertight manner using similar means to the above-mentioned case, thereby manufacturing the elbow E.
Also, in place of the above-mentioned sheet-shaped connecting material, there is also used means in which glass fiber sheets are stuck on the outer peripheries of the butted surfaces F, F in several layers using fused resin.
As described above, in the conventional spirally corrugated pipe elbow E of this type, there is employed the above means that spirally corrugated pipe body is cut at a required angle to two pipe bodies, one of the two divided pipe bodies is turned 180xc2x0 with respect to the other to change the respective angles of the cut surfaces of the two pipe bodies, the cut surfaces of the two pipe bodies are then butted against each other, and the thus butted surfaces of the two pipe bodies are connected together in a watertight manner over the whole peripheries thereof. However, this means raises a problem that it requires great trouble and time as well as a skilled technique; and, this means also raises another problem that the mutually butted surfaces of the two pipe bodies, including large spaces produced between the butted surfaces due to the mutual deviations between the spirally corrugated portions of the two pipe bodies, must be positively closed over the entire peripheries thereof and thus must be connected together in a watertight manner. Also, in the conventional spirally corrugated pipe elbow E, there is found a further problem that, even in case where the elbow E is manufactured with the great time and trouble taken, the connected portions of the elbow E obtained over the whole periphery thereof can be damaged in part due to vibrations produced during delivery of the elbow E, or due to improper handling of the elbow E, or due to biased loads such as uneven ground pressures applied to the elbow E after it is embedded into the ground, which gives rise to easy leakage of water.
In view of the above, the present invention aims at reducing and solving the above-mentioned problems found in the conventional elbow and in the conventional method for manufacturing the same. Accordingly, it is an object of the invention to provide an elbow having a structure free from the above water leakage and a method capable of manufacturing such elbow easily and quickly.
In attaining the above object, according to a first aspect of the invention, there is provided a first structure for an elbow. Referring to the first structure using reference characters used in the below-mentioned preferred embodiments of the invention, after a bend forming portion of a pipe body P having a given length and including a spirally corrugated pipe wall 1, with a partial portion a of the pipe wall 1 existing in the peripheral direction of the pipe body P left uncut, is cut and removed from the pipe body P in the form of a cut portion having a substantially V-like shape when it is viewed from the side surface side thereof, the thus obtained two cut surfaces are then bent and contacted with each other with the uncut pipe wall portion a set on the large diameter side, and the thus contacted portions t are connected together in a watertight manner using connecting material m.
Also, in the case of a second structure according to the invention, a bend forming portion of a pipe body P having a given length and including a spirally corrugated pipe wall 1, with a partial portion a of the pipe wall 1 existing in the peripheral direction of the pipe body P left uncut, is cut and removed from the pipe body P in the form of a cut portion having a substantially V-like shape when it is viewed from the side surface side thereof, and the mutually opposing cut bottom portions (e), (e) of the V-shaped cut portion are cut and removed in such a manner that they are shifted substantially by one pitch width r of the spirally corrugated shape of the pipe wall 1 in the axial direction of the pipe body P; and, after then, the thus obtained cut surfaces are bent and contacted with each other with the uncut pipe wall portion a set on the large diameter side, the crown portions 2 of the spirally corrugated shapes of the cut surfaces are contacted with each other substantially in a mutually opposing manner and the valley portions 3 of the spirally corrugated shapes of the cut surfaces are also contacted with each other substantially in a mutually opposing manner, and the outer peripheral surfaces of the contact portions t are connected together in a watertight manner using connecting material m.
And, according to another aspect of the invention, there is provided a method for manufacturing an elbow having the above-mentioned first structure. The present elbow manufacturing method executes sequentially the following steps of: cutting and removing a bend forming portion of a pipe body P having a given short length and including a spirally corrugated pipe wall 1 from the pipe body P in the form of a cut portion having a V-like shape when it is viewed from the side surface side thereof, while a partial portion a of the pipe wall 1 existing in the peripheral direction of the pipe body P is left uncut; bending the two side portions of the pipe body P with the uncut pipe wall portion a set on the large diameter side, and then contacting the cut surfaces (c), (c) with each other; and, while maintaining the bent state, connecting together the outer peripheral surfaces of the contact portions t of the cut surfaces c, c in a watertight manner using connecting material m.
Further, according to a further aspect of the invention, there is provided a method for manufacturing an elbow having the above-mentioned second structure. The present elbow manufacturing method executes sequentially the following steps of: cutting a bend forming portion of a pipe body P having a given short length and including a spirally corrugated pipe wall 1 from the pipe body P in the form of a cut portion having a V-like shape when it is viewed from a side surface side thereof, while a partial portion a of the pipe wall 1 existing in the peripheral direction of the pipe body P is left uncut, in such a manner that the mutually opposing cut bottom portions e, e of the V-shaped cut portion are shifted substantially by one pitch width r of the spirally corrugated shape of the pipe wall 1 in the axial direction of the pipe body P; removing the cut portion 4; bending the two side portions of the pipe body P respectively existing on the two sides of the uncut pipe wall portion a with the uncut pipe wall portion a set on the large diameter side to thereby substantially match the crown portions (2) of the spiral corrugated shapes of the cut surfaces to each other as well as substantially match the valley portions 3 thereof to each other, and then contacting the cut surfaces c, c with each other; and, while maintaining the above bent state, connecting together the outer peripheral surfaces of the contact portions t of the cut surfaces c, c in a watertight manner using connecting material m.
When enforcing the above-structured elbow, from the viewpoint of the pipe wall structure of a pipe body used as a blank member, there may be used a pipe body having a single wall structure formed in a spirally corrugated shape, or a pipe body having a dual wall structure including a corrugated main wall and an inner wall provided inside the main wall; or, in case where a pipe body to be connected to the present elbow is of a type that it is inserted into and connected to the interior portion of the elbow, there may be used a pipe body structured such that its outer periphery is formed in a smooth wall and its interior portion is formed in a spirally corrugated shape. Also, while the synthetic resin blank material of the pipe body is not limited to specific resin, preferably, there may be used blank material which is highly waterproof and weatherproof, such as polyolefin-system resin or vinyl chloride resin.
As the connecting means for connecting together the contact portions t, resin blank material having the same properties as the pipe body forming blank material or resin blank material highly fusion-weldable to the pipe body forming blank material may be applied to the contact portions t in such a state that it is heated and melted, or adhesives may be applied to the contact portions t, or sheet-shaped blank member may be attached to the contact portions t using the above-mentioned fusion-weldable resin or adhesives. Also, preferably, these connecting blank materials may be highly waterproof or weatherproof.